Zea mays (corn) is a graminoid, monoecious, annual plant that was domesticated in Mexico over 7,000 years ago. It was bred from wild corn and/or teosinte to become a staple food in many regions of the world, including the United States. Corn is by far the largest component of global coarse-grain trade, accounting for about three-quarters of total volume in recent years (coarse grains make up a common trade category that includes corn, sorghum, barley, oats, and rye). Because corn is sensitive to cold, in the temperate zones, corn is typically planted in the spring. As a C4 plant, corn is a typically more water-efficient than C3 plants like the small grains, alfalfa and soybeans. Nevertheless, corn is dependent on soil moisture because of its shallow root system. The importance of soil moisture is apparent in many parts of Africa, where periodic drought regularly causes corn crop to fail. Corn is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. Once established, corn can grow well over ten feet in height, capturing a significant amount of solar energy in the form of cellulose.
Corn can be used in a variety of ways. Corn can be used as forage, silage or feed for livestock. Feed corn is used to generate heat by burning corn in stoves (similar to wood stoves). Sugars in corn are exploited to produce syrups, particularly high fructose corn syrup, and can be fermented and distilled to produce grain alcohol. It is processed into a multitude of food and industrial products including starch, corn oil, and fuel ethanol. Increasingly, corn is being used to produce ethanol as a way to reduce fuel costs. More efficient methods of converting cellulose into ethanol are being developed.
Despite the many advantages afforded by corn, there is a vital need to create better plants if we are to meet the ever increasing demand for energy and nutrition around the globe. Crop plants that will increase hardiness and yield, reduce need for nitrogen and other chemical fertilizers, and allow propagation under a wide variety of growing conditions can help alleviate the problem.
Crop plants with improved characteristics can be obtained through breeding. Breeding programs can be designed to modify plant characteristics suited to particular growing conditions. Breeding programs are greatly aided by molecular markers that may be associated with specific traits of interest. Alternatively, molecular genetics approaches also allow production of plants tailored to grow more efficiently and produce more product in unique geographic and/or climatic environments. To this end, there is an ongoing need for genetic sequences and materials to advantageously manipulate plant characteristics such as architecture, biomass, development, composition, conversion efficiency, energy output, confinement, nitrogen use, nutrient uptake, phosphate use, photosynthetic capacity, shade avoidance, cold tolerance, drought tolerance, water use efficiency, stress tolerance, vigor, flowering time and yield to maximize the benefits of energy crops and other economically important crops depending on the benefit sought and the particular environment in which the crop must grow. Such advantageous manipulation of plants can be achieved with molecules from corn as described herein, which may simply be expressed or expressed at a higher or lower level in corn or other species.